Summary Aim. We investigated the occurrence and thrombin generating mechanisms of circulating microparticles (MP) in patients with multiple organ dysfunction syndrome (MODS) and sepsis. Methods. MP, isolated from blood of patients (n = 9) and healthy controls (n = 14), were stained with cell-specific monoclonal antibodies (MoAbs) or anti-tissue factor (anti-TF) MoAb and annexin V, and analyzed by flow cytometry. To assess their thrombin-generating capacity, MP were reconstituted in normal plasma. The coagulation activation status in vivo was quantified by plasma prothrombin fragment F1+2- and thrombin-antithrombin (TAT) measurements. Results. Annexin V-positive MP in the patients originated predominantly from platelets (PMP), and to a lesser extent from erythrocytes, endothelial cells (EMP) and granulocytes (GMP). Compared to healthy controls, the numbers of annexin V-positive PMP and TF-exposing MP were decreased (p = <0.001 for both), EMP were decreased (E-selectin, p = 0.003) or found equal (CD144, p = 0.063), erythrocyte-derived MP were equal (p = 0.726), and GMP were increased (p = 0.008). GMP numbers correlated with plasma concentrations of elastase (r = 0.70, p = 0.036), but not with C-reactive-protein or interleukin-6 concentrations. Patient samples also contained reduced numbers of annexin V-negative PMP, and increased numbers of erythrocyte-derived MP and GMP (p = 0.005, p = 0.021 and p <0.001, respectively). Patient MP triggered thrombin formation, which was reduced compared to the healthy controls (p = 0.008) and strongly inhibited by an anti-factor XII MoAb (two patients), by anti-factor XI MoAb (eight patients) or by anti-TF MoAb (four patients). Concentrations of F1+2 and TAT were elevated (p = 0.005 and p = 0.001, respectively) and correlated inversely with the number of circulating MP (and r = –0.51, p = 0.013, and r = –0.65, p = 0.001, respectively) and their thrombin generation capacity (F1+2: r = –0.62, p = 0.013). Conclusions. In patients with MODS and sepsis relatively low numbers of MP are present that differ from controls in their cellular origin, numbers and coagulation activation mechanisms.

BackgroundInterpretation of serological assays in Lyme borreliosis requires an understanding of the clinical indications and the limitations of the currently available tests. We therefore systematically reviewed the accuracy of serological tests for the diagnosis of Lyme borreliosis in Europe.MethodsWe searched EMBASE en MEDLINE and contacted experts. Studies evaluating the diagnostic accuracy of serological assays for Lyme borreliosis in Europe were eligible. Study selection and data-extraction were done by two authors independently. We assessed study quality using the QUADAS-2 checklist. We used a hierarchical summary ROC meta-regression method for the meta-analyses. Potential sources of heterogeneity were test-type, commercial or in-house, Ig-type, antigen type and study quality. These were added as covariates to the model, to assess their effect on test accuracy.ResultsSeventy-eight studies evaluating an Enzyme-Linked ImmunoSorbent assay (ELISA) or an immunoblot assay against a reference standard of clinical criteria were included. None of the studies had low risk of bias for all QUADAS-2 domains. Sensitivity was highly heterogeneous, with summary estimates: erythema migrans 50 % (95 % CI 40 % to 61 %); neuroborreliosis 77 % (95 % CI 67 % to 85 %); acrodermatitis chronica atrophicans 97 % (95 % CI 94 % to 99 %); unspecified Lyme borreliosis 73 % (95 % CI 53 % to 87 %). Specificity was around 95 % in studies with healthy controls, but around 80 % in cross-sectional studies. Two-tiered algorithms or antibody indices did not outperform single test approaches.ConclusionsThe observed heterogeneity and risk of bias complicate the extrapolation of our results to clinical practice. The usefulness of the serological tests for Lyme disease depends on the pre-test probability and subsequent predictive values in the setting where the tests are being used. Future diagnostic accuracy studies should be prospectively planned cross-sectional studies, done in settings where the test will be used in practice.

dAvibactam is a new non-␤-lactam ␤-lactamase inhibitor that shows promising restoration of ceftazidime activity against microorganisms producing Ambler class A extended-spectrum ␤-lactamases (ESBLs) and carbapenemases such as KPCs, class C ␤-lactamases (AmpC), and some class D enzymes. To determine optimal dosing combinations of ceftazidime-avibactam for treating infections with ceftazidime-resistant Pseudomonas aeruginosa, pharmacodynamic responses were explored in murine neutropenic thigh and lung infection models. Exposure-response relationships for ceftazidime monotherapy were determined first. Subsequently, the efficacy of adding avibactam every 2 h (q2h) or q8h to a fixed q2h dose of ceftazidime was determined in lung infection for two strains. Dosing avibactam q2h was significantly more efficacious, reducing the avibactam daily dose for static effect by factors of 2.7 and 10.1, whereas the mean percentage of the dosing interval that free drug concentrations remain above the threshold concentration of 1 mg/liter (%fT>C T 1 mg/liter) yielding bacteriostasis was similar for both regimens, with mean values of 21.6 (q2h) and 18.5 (q8h). Dose fractionation studies of avibactam in both the thigh and lung models indicated that the effect of avibactam correlated well with %fT>C T 1 mg/liter. This parameter of avibactam was further explored for four P. aeruginosa strains in the lung model and six in the thigh model. Parameter estimates of %fT>C T 1 mg/liter for avibactam ranged from 0 to 21.4% in the lung model and from 14.1 to 62.5% in the thigh model to achieve stasis. In conclusion, addition of avibactam enhanced the effect of ceftazidime, which was more pronounced at frequent dosing and well related with %fT>C T 1 mg/ liter. The thigh model appeared more stringent, with higher values, ranging up to 62.5% fT>C T 1 mg/liter, required for a static effect.A ll over the world, health care professionals are struggling with the problem of antibiotic resistance, and extended-spectrum ␤-lactamase (ESBL)-and/or carbapenemase-producing microorganisms especially form a global threat (1-7). Apart from antibiotic stewardship, vaccines, and hygiene measurements, the development of new classes of antibiotics is of life-saving importance. Another, previously successful approach to overcome resistance is to combine a clinically proven ␤-lactam antibiotic with an inhibitor of the ␤-lactamases that confer resistance to it.AstraZeneca and Actavis (formerly Forest-Cerexa) are developing the combination of ceftazidime with avibactam, a new non-␤-lactam ␤-lactamase inhibitor that forms a hydrolytically stable linkage with serine-based ␤-lactamases to overcome resistance (8, 9). The combination showed in vitro activity against Ambler class A ESBLs, KPC class A enzymes, class C (AmpC) enzymes, and some class D enzymes. Studies in vitro have shown that ceftazidime MIC values against resistant strains were reduced drastically in the presence of this inhibitor, causing the strains to become susceptible to ceftazidime (9, 10). In dose-respo...

Results of QFT-Plus are highly comparable to QFT-GIT. Although there is an indication that a true difference in interferon-γ release between the antigen tubes is associated with recent latent tuberculosis infection, the QFT-Plus could not be used to exclude recent exposure.

No abstract

C eftazidime (CAZ) is a potent ␤-lactam antibiotic against Gram-negative bacteria in particular (1). However, since more and more Gram-negative bacteria have emerged that carry extended-spectrum ␤-lactamases (ESBLs) (2, 3) and class C ␤-lactamases (4), resistance has led to difficulty in identifying ␤-lactam therapies that would minimize the risk of resistance-related failure (5). Moreover, Klebsiella pneumoniae carbapenemase (KPC) and OXA-48 carbapenemase are narrowing treatment options against Gram-negative bacteria even further (6-8). For this reason, alternatives have been sought. The use of ␤-lactamase inhibitors seems to be a reasonable approach, and combinations consisting of a ␤-lactam agent and a ␤-lactamase inhibitor, such as piperacillintazobactam and amoxicillin-clavulanic acid, are widely used. AstraZeneca and Actavis (formerly Forest-Cerexa) are developing a combination of ceftazidime (CAZ) with avibactam, a new promising ␤-lactamase inhibitor, to overcome resistance caused by ␤-lactamases (9, 10). This combination has an extended spectrum of activity and is active against Ambler class A extended-spectrum ␤-lactamases (ESBLs), KPC class A enzymes, class C (AmpC) enzymes, and some class D enzymes (11)(12)(13)(14)(15). In vitro studies have shown that the drug MIC values for resistant clinical isolates, including Pseudomonas aeruginosa, were drastically reduced in the presence of this inhibitor and that the isolates thereby became susceptible to ceftazidime (11,(16)(17)(18)(19). Activity of the inhibitor in vivo has been shown as well (see, e.g., reference 13).As pneumonia is one of the leading causes of death in humans (20) and treatments using several new compounds have failed in patients with lower respiratory tract infections (21,22), it is important to understand the mechanism of activity, including the pharmacokinetic/pharmacodynamic (PK/PD) properties of the drugs used for this indication. For the combination ceftazidimeavibactam, concentrations of ceftazidime and avibactam in the lungs relative to each other might be different from the relative concentrations in plasma and therefore might result in bacterial responses in lung infection that are different from those in infections in other tissues.In the present study, we determined the pharmacokinetics of ceftazidime and avibactam and concentration-time profiles of the two compounds relative to each other in plasma and epithelial lining fluid (ELF) of infected neutropenic mice. Both thigh infection and lung infection models were used, to determine whether different kinds of infections would have different impacts on the pharmacokinetic profiles of each compound. The pharmacokinetic parameter estimates and the penetration of the two com-

dTo evaluate the in vitro effects of the combination of ceftazidime and avibactam on the MICs of both compounds, checkerboard assays were performed for 81 clinical strains, including 55 Enterobacteriaceae strains (32 Klebsiella pneumoniae, 19 Escherichia coli, 1 Citrobacter freundii, and 3 Enterobacter cloacae) and 26 strains of Pseudomonas aeruginosa, all with known resistance mechanisms such as extended-spectrum ␤-lactamases (ESBLs) and carbapenemases, phenotypically or molecularly determined. Phenotypically ceftazidime-resistant strains (n ‫؍‬ 69) were analyzed in more detail. For the Enterobacteriaceae strains, a concentration-dependent effect of avibactam was found for most strains with a maximum effect of avibactam at a concentration of 4 mg/liter, which decreased all ceftazidime MICs to <4 mg/liter. Avibactam alone also showed antibacterial activity (the MIC 50 and MIC 90 being 8 and 16 mg/liter, respectively). For the ceftazidime-resistant P. aeruginosa strains, considerable inhibition of ␤-lactamases by avibactam was acquired at a concentration of 4 mg/liter, which decreased all ceftazidime MICs except one to <8 mg/liter (the CLSI and EUCAST susceptible breakpoint). Increasing the concentration of avibactam further decreased the MICs, resulting in a maximum effect for most strains at 8 to 16 mg/liter. In summary, for most strains, the tested addition of avibactam of 4 mg/liter restored the antibacterial activity of ceftazidime to a level comparable to that of wild-type strains, indicating full inhibition, and strains became susceptible according to the EUCAST and CLSI criteria. Based on these in vitro data, avibactam is a promising inhibitor of different ␤-lactamases, including ESBLs and carbapenemases.A ntibiotic resistance is a worldwide problem. Until the past decade, the development of new classes of antibiotics was an important weapon against development of resistance. However, strains that carry extended-spectrum ␤-lactamases and/or carbapenemases have emerged (1, 2). In some countries, the resistance levels to these drugs are now Ͼ50% (3). One approach for overcoming this mechanism of resistance is by inhibition of these enzymes. This approach has been taken in the past against ␤-lactamase-carrying strains using drug combinations consisting of a ␤-lactam agent and a ␤-lactamase inhibitor (4-11), such as piperacillin-tazobactam and amoxicillin-clavulanic acid. These have been and still are among the most successful antimicrobials available.Among several new ␤-lactamase inhibitors and combinations with ␤-lactams that are currently being developed is avibactam (12, 13). This compound is active against Ambler class A extendedspectrum ␤-lactamases (ESBLs) (e.g., TEM, SHV, and CTX-M types), KPC class A enzymes, class C (AmpC), and some class D enzymes. Studies in vitro (14-24) have shown that the MICs of ceftazidime for many resistant strains were markedly reduced in the presence of avibactam and thereby became susceptible.An important step in the development of a combination ␤-lactam-␤-lactamase inhib...

In view of the results of animal studies as well as theoretical considerations, continuous administration of ␤-lactam antibiotics should be superior to intermittent administration because of the close relationship between efficacy and the duration of time in which the concentration of unbound antibiotics in plasma remains above the MIC. The aim of the present study was to establish the pharmacokinetic parameters of cefamandole and ceftazidime for patients receiving these cephalosporins by continuous infusion. The interindividual differences in the concentrations in plasma at the steady state were mainly attributable to variations in renal function, as estimated by the rate of creatinine clearance. Using these results, we derived formulas for both cephalosporins that can be used to determine on an individual basis the total daily dose needed to obtain a therapeutic concentration in plasma. These formulas were tested with a group of subsequent patients and proved to be practical and fairly reliable. For some patients, a correction for a possible underestimation of the renal clearance at presentation might be required.For ␤-lactam antibiotics, the maximal bactericidal effect is reached in vitro at relatively low concentrations. Increasing the concentration further does not appear to have any additional effect (3). This means that the range within which the antimicrobial effect is concentration dependent is rather narrow. This knowledge can be used for optimizing dosing regimens.In experimental infections in granulocytopenic animals, the antimicrobial effect of ␤-lactam antibiotics was closely related to the duration of time that the concentration of the drug in plasma remained above the MIC (1,2,5,7,9,11,12,14).The half-life of most ␤-lactam antibiotics in humans is relatively short and is often not longer than 2 h. Doubling the dose prolongs by only one half-life of the drug the time during which the concentration in plasma remains above the effective concentration. To obtain a maximal effect in patients with serious infections, therefore, a more efficient way to keep the concentration in plasma from falling below the MIC long before the end of the dose interval would be to decrease the dose interval rather than to increase the dose. If this were to lead to very frequent dosing, continuous infusion of the drug would be preferable to intermittent administration.To properly treat patients by continuous infusion of antibiotics, the pharmacokinetics during this procedure, in particular in relation to renal function, should be known. Cefamandole and ceftazidime are often used for the treatment of serious gram-negative infections, with the choice depending on the expected or established sensitivity of the causative microorganism.The present study was undertaken to establish the pharmacokinetics of those two antibiotics during continuous infusion.As a first step, we determined the relationship between concentration in plasma, renal clearance, and nonrenal clearance. To validate these results, they were used to obtain pre...